Aspects of the present invention relate generally to the field of cellular communications, and more specifically to improving the user equipment transition from a PCH state to a DCH state for the anticipated transmission of large amounts of data on UMTS.
Generally, for terminals, client devices or user equipment (UE) communicating in accordance with the Universal Mobile Telecommunications System (UMTS) standard, the UE connected to the cellular telecommunications network will conventionally have four potential non-idle states once a Radio Resource Control (RRC) connection has been established: CELL_DCH, CELL_FACH, CELL_PCH, and URA_PCH. In the CELL_DCH state, dedicated channels for uplink and downlink to the UE are allocated for the transmission/reception of data. The CELL_DCH state is suitable for the transmission of large amounts of data. In the CELL_FACH state, no physical channel is dedicated to the UE, but a forward access channel (FACH) is continuously monitored by the UE for downlink and a default common or shared transport channel is assigned for uplink transmissions. The CELL_FACH state is suitable for the transmission of small amounts of data. In the CELL_PCH state, no physical channel is dedicated to the UE and no uplink activity is possible. However, in CELL_PCH, a paging channel (PCH) is monitored by the UE for downlink. Similarly, in the URA_PCH state, no physical channel is dedicated to the UE, no uplink activity is possible, and a paging channel is monitored by the UE for downlink notifications. Both the CELL_PCH and URA_PCH states are suitable for the UE to save battery when no data is actively being exchanged.
Conventionally, a UE in idle state transitions to a connected CELL_FACH or CELL_DCH state when a network connection is established. Then additional state transitions are based on the activity and the amount of data in the buffer for transmission. For example, when in CELL_DCH state, if the delay in transmission activity exceeds a predetermined threshold, then the UE may be transitioned to the CELL_FACH state. When in the CELL_FACH state, if the activity level drops below a predetermined threshold, the UE may be transitioned to CELL_PCH or URA_PCH state.
The UE may be transitioned from CELL_PCH to CELL_FACH and from URA_PCH to CELL_FACH upon detection of activity requiring a forward access channel or an uplink channel. When in CELL_FACH, if the amount of data awaiting transmission on the channel exceeds a predetermined threshold, the UE may be transitioned to CELL_DCH state. The network system will assign a dedicated channel to the UE for transmission of the data. For example, in the case of an uplink FTP transfer, with a UE in the CELL_PCH state, the UE will initially transition to CELL_FACH to manage the TCP handshake and initiate the FTP session. Then, once the data transmission has begun, the data waiting to be transmitted may be measured, a dedicated channel may be allocated, and the UE will be transitioned from the CELL_FACH to the CELL_DCH state.
From the CELL_PCH or URA_PCH state, the UE may transmit a cell update message with the Traffic Volume Indicator (TVI) flag set. Conventionally, the TVI information element in a cell update message indicates that the UE has more data in its MAC buffer than a predetermined threshold. The predetermined threshold is typically configurable by the network in order to manage efficient allocation of channel resources. This would conventionally trigger the network to switch the UE to CELL_DCH directly.
Therefore, in order to transmit information on the network, when the TVI flag is not set, the UE is first transitioned from the URA_PCH or CELL_PCH state to the CELL_FACH state and then from the CELL_FACH state to the CELL_DCH state. However, if the data to be transmitted is known by UE prior to initiating the transmission, or when the UE otherwise detects that a dedicated channel will be required for a transmission, the transition from a PCH state to the CELL_FACH state and then to the CELL_DCH state causes unnecessary delay. Additionally, with each state switch, there are additional opportunities for network and transmission errors. Accordingly, there is a need in the art to expedite the UE switch to a DCH state for the anticipated transmission of large amount of data over the cellular network.